Two stage retractable float for aircraft



Aug. 7, 195] E. J. NICHOLL TWO STAGE RETRACTABLE FLOAT FOR AIRCRAFT 8 Sheets-Sheet 1 Filed Oct. 23,

Aug. 7, 195] E. J. NICHOLL TWO STAGE RETRACTABLE FLOAT FOR AIRCRAFT 8 Sheets-Sheet 2 Filed Oct. 25, 1948 Aug. '7, 1951 E. J. NICHOLL TWO STAGE RETRACTABLE FLOAT FOR AIRCRAFT 8 Sheets-Shet 5 Filed Oct. 23, 1948 E. J. NICHOLL TWO STAGE RETRACTABLE FLOAT FOR AIRCRAFT Aug. 7, 1951 8 Sheets-Sheet 4 Filed Oct. 23, 1948 7, 5 E. J. NICHOLL 2,563,263

TWO STAGE RETRACTABLE FLOAT FOR AIRCRAFT Filed 001;. 23, 1948 8 Sheets-Sheet 5 .5 45 O\ q 0 i 45 37 25 23 v g- 7, 1951 E- J. NICHOLL 2,563,263

TWO STAGE RETRACTABLE FLOAT FOR AIRCRAFT Filed 0612. 2:5, 1948 8 Sheets-Sheet 6 lli J fawn 4 47m: law. 4/ M M 3:04 nod/$ 7] 1951 E. J. NICHOLL 2,563,263

TWO STAGE RETRACTABLE FLOAT FOR AIRCRAFT A Filed Oct. 25, 1948 a Sheet s-Sheet 7 I w \w .J\J\\\@HA \J z n A .M Q Q Aug 1951 E. J. NICHOLL 2,563,253

TWO STAGE RETRACTABLE FLOAT FOR AIRCRAFT /Y rzarr n' Iowa 4- Jivns: /G//o 41.

Patented Aug. 7, 1951 TWO STAGERETRACTABLE FLOAT FOR AIRCRAFT Edward JamesNicholl, Cheltenham, England, as-

signor to Saunders-Roe Limited, Osborne, East Cowes, Isle-of-Wight, England Application October 23, 1948, Serial No. 56,146

'In-Grea't Britain November 6, 1947 12 Claims. 1

In United States Patent No. 2,285,330 there is described an aircraft provided with laterally retractable stabilising ifloats, each formed of :separate watertight portions connected by a fore and aft hinged joint which is 'closed'in the down position of the :float but is arranged to "open, as the float is retracted, to permit of separation .of the two portions thereof and their accommodation in separate .recesses :in the wing.

Splitting the float in this fashion has the advantage that it is possible to employ a float :of suflicient depth for it to serve asan-eflective lateral stabilizer and nevertheless, owing to thefact that the two portions thereof separate during retraction, to retract the floatcompletely into a thin wing.

In the arrangement described andiil-lustrated in United States Patent No. 2,285,330 the'retraction of the split float is effected in a single stage, the float being connected to the wing by-a system v of struts so disposed that the two portions of the float separate during the movement of the float from the down to the retracted position and are completelyseparated by the time they are moved simultaneously into their wing recesses.

I now find that it is advantageous to conduct the retraction in .twostages and to defer separation of the .twoportions of the float until after thatportion of the float which is approaching the wing (i. e. the inboard portion when, as will .nor: mally be the case, the float is retracted in .an inboard direction) has been retracted into its wing recess, whereafter, as a second stage operation, the other portion of the floatis caused to separate from its companion and move into its wing recess.

The advantages of such two-stage retraction are two-fold. Firstly, the aerodynamic loading on the float during its travel from'the down to the retracted position is reduced. The aerodynamic hinge movement curve obtained, in the case of two-stage retraction, consists of two peaks, each of which is'of half the magnitude-of the single peak obtained with the single-stage method. Therefore, although the average power required is the same'in both cases,-the peak power -is halve'd inthe two-stage case. Secondly, itis possible-in the case of two-stage retraction, to eliminate the cut-aways required inthe float itself to accommodate the strut which causes the float'to split. Separation of the two sections can, in theycase of two-stage retraction, 'be elTected, as later-explained, by a hydraulic jack fitted to the back of the *float. a

"The present invention accordingly provi'desin an aircraft, a laterally retractable stabilising float, split fore and aft into two portions, which float is retractable 'into the wing of the aircraft in two stages, the float moving as a unit during the first stage, Without separation of its constituent portions, to bring one "of said portions only into a recess in the wing, and the constituent portions of the float separating, during the second stage, to bring the other of said portions into a recess inthe wing.

The invention includes, in an aircraft, the combination with a stabilising ,fioat divided into two portions hinged together along the keel line, of a lock for holding the two portions together, means for retracting the float laterally, without release of the lock or separation of its two component portions, until oneportion thereof has entered a recess provided for its accommodation in the wing, and mechanism operative thereafter first to release the ,lock and then to swing the other portion of the float about the hinge to retract it intoa further recess in the wing.

Normally, the float will be retracted in an inboard direction, soas first of'all to bury the inboard portion of the float in its recess in the wing, whereafter release of the lock and-separation of the twoportions about the hinge are eifected to bury theoutboard portion of the float in its recess. On lowering the float, the reverse sequence ofoperations takes place, the outboard portion of the float first swinging about its hinge into mating relationshipwith the inboard 'portion, whereafter the lock is engaged and the complete float is lowered.

Preferably both the-first and second stages of retraction of the float are effected by means -'of hydraulic jacks, located respectively in the wing and in the float. Preferably also the lock'be tween the two portions ofthe float is likewis operated hydraulically;

One particular embodiment-of the invention will now be describedin detail, by way of example, with reference to thegaccompanying drawings, in which 4 v. 1

Fig. 1 is a front "elevations'howing the float the down position,

Fig. '2 is a similar view showing the position of the float after-the first stage of retraction,

Fig. 3 is a similar viewshowing the float after the second stage of retraction,

Fig. 4 is a plan view of the float in the fully retractedposition,

Flig 5 .1 circuit diagram showing the elec trical circuits controlling the operations of -rai's-'- mg and loweifin'g'the 'float -the stitches being shown in the positions they occupy when the float is down,

Fig. 6 is a hydraulic circuit diagram, showing the parts in the position they occupy when the float is down,

Figs. '7 and 8 show successive stages in operation of the change over valve shown in Fig. 6 as the float is raised,

Figs. 9-13 are circuit diagrams showing indicators and how they are operated at different stages in the retraction of the float.

Fig. 14 is a front elevation of one of the outboard up locks, showing the lock in disengaged position,

Fig. 15 is a corresponding end elevation,

Figs. 16 and 17 are respectively sections taken on the lines XVI-XVI and XVII-XVII in Fig. 15, Fig. 16 showing the lock engaged, and

Fig. 18 is a front elevation of the down lock.

Like reference characters designate like parts throughout the figures.

Referring first of all to Figs. l-4, the float is split vertically along its central longitudinal plane into two separate watertight portions 2!. 3| hinged together by a hinge 32 on the keel line and locked together by a float lock 20 near the upper end of the float when the float is down. To the inboard portion 2| of the float are flxed a pair of aligned fore and aft struts 22, fixed at their upper ends to a shaft 23 in the wing 24, which shaft extends chordwise and is mounted for rotation in the wing. The shaft carries a projecting bifurcated arm 25 pivoted to the piston rod 26 of a float raising hydraulic jack .2? mounted in the wing and having its cylinder pivoted to the wing at the end '28 of the cylinder remote from the shaft. A down lock 29 in the wing ccacts with the arm 25 to lock the float in the down position, in which the piston rod 25 is retracted into the jack cylinder.

The operation of raising or lowering the floats is initiated by movement of a switch 30 (Fig. 5). When the floats are down, the switch 30 connects a 24-volt supply line 53 to a pair of down contacts 34 and to raise the floats the switch is moved to connect line 53 to a pair of up contacts 33. To lower the floats again, the switch 30 is moved back to contacts 34. As described later, indicators are provided for showing the pilot the position occupied by the floats and an additional indication is provided for him by the position of the switch 3|]. Movement of the switch 30 from one pair of contacts 33, 34 to the other, as described in detail later, completes circuits to energise the electric motors of a pair of power packs, one allocated to each float. One only of the power packs, and the hydraulic circuit for operating the associated float is shown in Fig. 6, but it will be understood that a precisely similar power pack, hydraulic circuit, locks, jacks and indicators are associated with the other float, so that a description of the raising and lowering of one of the floats will be sufficient, the other being operated in precisely similar fashion. Each power pack consists of an electric motor 35 (Fig. 6) and a hydraulic pump 36 driven thereby.

When the power pack is set in operation with the float down, hydraulic pressure is first applied, as described in detail later, to the down lock 29, to withdraw it from the arm 25, and then to the jack 21, causing the piston rod 26 to be projected from the jack cylinder and to rotate the shaft 23, clockwise as seen in Fig. 1, to cause inboard retraction of the float through approximately 90", the two portions 2|, 3! of the automatically operated, by contact of the inboard portion 2| of the float therewith, to lock said inboard portion 2| in the up position. At this stage the outboard portion 3| of the float projects beneath the wing, the plane of division of the two portions being flush with the undersurface of the wing. Operation of the outboard up locks 31 actuates a magnetic sequence valve 38 (Fig. 6) as later described to cause hydraulic .pressure to be supplied firstly to release the float lock 20 and permit of separation of the two portions thereof, and secondly to a float splitting jack 39 in the float. It will be noted from Fig. 4 that the jack 39 is fitted to the back of the float. The cylinder of the jack 39 is pivoted at 49 to the inboard portion 2| of the float and its piston rod 4|, which is projected from the cylinder in the position shown in Figs. 1 and 2, is pivoted at 42 to a pair of triangular levers 43 which are rotatably mounted at 44 on the inboard portion of the float. The levers 43 are pivoted at 45 to one end of a link 46, the other end 41 of which is pivoted to the outboard portion 3| of the float.

Supply of hydraulic fluid to the float jack 39, after the float lock 20 has been released, causes the piston rod 4| to be retracted, so opening out the outboard portion 3| of the float and rotating it through to the position shown in Fig. 3 to retract it completely into a recess in the wing, in which it is automatically locked by engagement of the outboard portion with an inboard up look 48 in the recess.

When it is desired to lower the float, the sequence of operations is reversed. First the inboard up look 48 is released hydraulically and pressure is supplied to the float jack 39 to cause the outboard portion 3| to collapse against the inboard portion 2|, the float lock 20 automatically locking the two portions of the float together when contacted by the returning outboard portion. The float has then attained the position of Fig. 2. The float lock 20, when actuated to lock the two portions of the float together, automatically operates a valve 49 (Fig. 6) to cause hydraulic pressure to be supplied firstly to the outboard up locks 31 of the float to release these locks, and secondly to the float raising jack 21, which thereupon returns the float to the lowered position (Fig. 1) in which it is automatically locked by the down lock 29 associated with the arm 25.

All of the locks, viz. the down lock 29, the float lock 20, the outboard up locks 31 and the inboard up look 48 are mechanically closed but are opened by hydraulic pressure. Associated with each lock is a pair of micro-switches which are operated, as later described, when the lock is fully closed. One microswitch of each pair controls the indicator circuits shown in Figs. 9-13 and is identified by the numeral of its associated lock and the suffix a. In the down position of the float, shown in Fig. 9, a circuit is completed to earth, from a line 50, through the float lock switch 20 and the down lock switch 29 to light a green lamp 5|. After the down lock 29 has opened, the switch 29 moves to the position of Fig. 10, and during transit of the float from the position oi' Fig. '1 to that of Fig. 2 a -"circuit :is completed, through the switches 29 outboard up -locksswitches 31 1 inboard :.up lock switch 48*, and-a relay switch 6!! '(the last'iour switches in parallel) to light a red'lamp 52. 'R'elay'switch Bil -is closed when arelay 60 (Fig. 5) is energised, as later described, to switch on the power pack motor. When the float has been locked by the outboard up locksin the position'shown in'FigfZ, the switches 3' move to the position shown in Fig. '11. A circuit is'nevertheless still completed to'light the'red lamp 52'through'theswitches 61'1' and 46 When thefloat'lock hasopenedthe switch ill moves to the position of Fig. 12 "and while the float is in transit'from the position of Fig. 2'to that of Fig. 3, the red-lamp 52'continues to be'lighted as shown in'Fig. .12. Finally, when the float has'been lockedin the position-of Fig. 3 by closure of the inboardrup lock,'therelay 60 is tie-energised, as later; described, "to open the switch 60*, switch 48* ha's also opened,.'a'n'd both lamps'5'l, 52 are off as showniniFig. 13.

The other microswitch of each pair controls the "circuits shown'in'Fig. 5. Each such switch isdesignated by the numeral applied to its associated lock, with the suflix b. When the outboard up locks '3! are unlocked, the circuit through the associated microswitches 31 is broken. When theinboard up look is unlocked, the circuit through its associated microswitch 48 is made. "When the .float llockzn and down lock are unlocked, circuits through theirassociated microswitches 25 w ere made.

Fig. 5 shows the conditions prevailing when the float is down. Movement of the switch 36 from contacts .34 to contacts -33 completes a circuit from .line 53 and through limit switch I55 to start a reversible motor 55 having -field windings .260, .300. Under these conditions field winding .266 is operative and the motor rotates in the direction to move .a rotary control valve 56 clockwise from the position shown in full .lines in .Fig. 6 to its alternative position, shown in chain-dotted lines,.for raising the floats. In the full line position of the valve 56 shown in Fig. 6, its passage i56 connects lines -85, .81 and its passage 2-5 6 connects lines 86, -88-and this is the position appropriate for lowering the floats. Clockwise rotationof the valve 56 through 90 will, however, cause the passage 156 t connect lines 87, 88 .and thepassage 2 56 to connect lines 85, 86 and this is the position appropriat for raising the floats. When the valve 56 has been rotated clockwise through 90, the .limitswitch I55 moves from its contact 255 to its contact 355, thereby stopping the motor 55. Movement of the switch 36 from contacts 34 to contacts 33 also completes a circuit .from line 53, through the closed switch-dfi andrelayfill toearth, thereby energising the .relay and closing switch 60 (see also Figs. 9-13) and switches 60 and 66. Closure of 'switch 6ll completes a circuit from :a 120 :volt supply line 5'4 to start the power pack motor :35.

When the host has reached the position of Fig. 2, and the outboard up locks 31'h'ave closed, a circuit is completed from line :53 through switches 60 and 31 to energise a solenoid 58 for operating the magnetic sequence valve 38 (Fig. 6) previously referred to. This valve is normallyheld closed by aspring 59, but is opened magnetically, by energisation-of the solenoid 58, to supply hydraulic pressure to the fioat lock 20 .andlto the .float splitting Jack-.39. When the 6 float :ha's TmOVEd to :the. position of "Fig. :3, and thefinboard unlock-48 has closed, the switch-48 (Fig. .5) -opens ;to ole-energise the :relay .60, Open contacts 60 and stop the power pack motor.

When the :switch .30 is thereafter returned :to contacts 34, a circuit is completed through .fleld winding 30.0 and limit switch I55 to start the motor 55 in :the reverse .direction. .This causes counterclockwise rotation .of the valve 56 (Fig. 6) through returning it to its full line .position, which is theposition suitable for lowering the floats. When the valve 56 has reached this position, the :limit switch I55 returns to contact 255 and the motor 55stops. Return of the switch 30 to contacts 34 also causes therelay fiflto-be energised through the switches 20 and 29 which arenow .closed. Closure of switch 60? starts the power pack motor 35 as before. The float is then lowered,.switch 20 being opened when the float lock Zllcloses. When switch .29 opens, as the result of closing of the down lock19, the relay 60 is ale-energised andthe motor-35 is therefore stopped.

Each of the outboard up locks 31 is of the construction'shown in Figs. .14-17. It-comprises a casing 6|, mounted within the wing structure. to which is pivoted on pins 62- a ,pair of hooks 63. At its upper end,ea'ch hook 63 has a projection 64 (Fig. 17), against which presses a pair of compression springs 65. The springs 65 thus normally'hold the hooks 63 in the position shown in .Fig. 14. As the inboard section II of the float ascends into the recess in the wing, a bar 66 carried by'the float moves up into position between the hooks, as shown in Fig. 17. As the bar 66 continues to ascend, it pushes the hooks aside and, when the upward movement of the float is completed, the :hooks snap back to lock the bar66 as'shown in Fig. 16. Pivotedat 61 to each hook isa lever 68. The levers 68 have slots 69 into which is fitted a pin 10 coupling the levers together. Torsion springs II normally maintain the levers 68 in the down position shown in Fig. 14. As the bar 66 passes intoposition between the hooks 63, however, it lifts the levers 68 and, when the hooks 63 snap back to lock the'bar 66, as shown in Fig. 16, extensions 12 of the levers 68 operate-the micr'oswitches 31 31 When the bar 66 is in a position between those shown in Figs. 16 and 17 the hooks 63 are held apart by the bar and the projections 12 can only make contact with the microswitches 31 and 3-1 when the'hooks have snapped back, so that the microswitches are not operated until the baris securely locked.

The outboard up locks thus close mechanically and by spring action. They are opened hydraulically. Each spring 65 is disposed ina cylinder 13. To open the lock, hydraulic pressure is supplied to a pressure inlet 14. and thence through passages ll4 (Fig. 17) to the two cylinders. The pressure so 'admittedfacts on a'piston 15 in each cylinder and,'by compressing thespring 65 ,'moves the associated hook 63 to openposition. Immediately therefore pressure is supplied to the'lock the hooks are moved to open position 'andremain open so long 'asthe pressure is'maint'ained. Ime mediately'theipressure is applied and the hooks move away from the closed position, the projections 12 are moved away from the microswitchesl.

The inboard up look 48 is of exactly similar construction, and a bar I66 (Fig. 1) similar to bar 66 'is'provided on the outboard section 3| of thefloat for engagement'withtm hooks of this look. The float lock 20f'is also similar, a bar 286, similar to bar 86, on the outboard section 3| of the float engaging the hooks of the float lock. The float lock, however, has to perform a further function, namely to open a mechanical sequence valve 49 (Fig. 6) when the lock closes. This valve is normally held closed by a spring I49, but when the float lock closes an extension, indicated in chain dotted lines at 16 in Fig. 16, one of the levers 68 coacts with the stem 11 of the valve 49 to open the valve.

The down lock 29 is of somewhat difierent construction and is shown in Fig. 18. A bar 365 on the arm 25 cooperates with a pair of pivoted hooks 18, only one of which is shown in Fig. 18, the other lying immediately behind it. Both hooks 19 are however seen in Fig. 4 The hooks are urged counterclockwise by springs similar to the springs 65 in Fig. 1'7. As the bar 355 descends, it pushes the hooks aside and they afterwards snap back to the position shown in Fig. 18 to lock the bar. On each hook 18 is pivoted, at 19, a lever 89. Each lever is associated with one of a pair of microswitches 29, 29 Normally each of the levers 89 is held, by a spring I89, with a lug 8| on its upper end resting on the upper edge of the associated hook 18. As the hooks snap back to lock the bar 366, the latter presses against the inner edges 82 of the levers and displaces them into the position shown in Fig. 18, in which pins 83 carried by the levers operate the microswitches. To open the lock, hydraulic pressure is applied to an inlet 84 and this pressure, acting on a pair of pistons similar to the pistons 15 in Fig. 17, compresses the springs and moves the hooks 18 to the open position, the levers 89 then being freed and being returned by their springs I89 to a position in which their pins 83 are clear of the microswitches 29 29 The complete sequence of operation on raising and lowering the floats, will now be explained with reference to Fi s. 6-8.

Raising the floats It has already been explained how movement tacts 34 to the "up contacts 33 starts the motor 35 of the power pack and also the motor 55 of the control valve 56, which is thereupon moved into the position shown in chain dotted lines in Fig. 6. The pump 38 then supplies oil under pressure from pressure line 85, via passage 258 in the valve, to line 86 and oil is returned, through the valve 56, from line 81 and passage I56 in the valve to the return line 88 of the pump. A relief valve 89 limits the oil pressure to 3009 lbs/sq. in. Oil flows from line 85 through a variable flow valve, constituted by a non-return valve 99 in parallel with a restricted passage I25, to the down lock 29 and opens that lock. As soon as the lock 29 has opened, the oil pressure overcomes the pressure of a spring 92 of a pressure sequence valve 9|, and passes into line 93 and thence to a change over valve 94 controlling operation of the float raising jack 21.

The retraction operation is carried out in two stages, in order to economise in power. Initially, hydraulic pressure is supplied to both ends of the cylinder of jack 21. During this initial stage in the retraction of the float the load imposed on the jack, by the weight of the float and the aerodynamic loading thereon, is small and the jack operates, despite the application of pressure to both ends of the cylinder, at high speed and low torque. As the float rises, the load imposed on the jack as the result of the moment about the axis of the shaft of the weight of the float and the aerodynamic loading on the float, rises. Therefore the torque and the delivery pressure of the pump rise, and when the delivery pressure reaches a predetermined value the changeover valve 94 operates automatically to connect the end of the jack cylinder from which the piston rod 26 projects to exhaust instead of to pressure. Thereafter the jack operates slowly and at high torque.

The change over valve operates as follows: When pressure is admitted to line 93, it at once operates directly on the right hand side of the jack piston. The change over valve comprises a pair of non-return valves 95, 96, a valve 91 loaded by a spring 98, a valve 99 normally held open by a spring I99 and carrying a piston IN a second piston I92 carrying a tappet I93 and normally held in the position shown in Fig. 6 by a spring I94, and a valve I95 normally held closed by a spring I96. When pressure is supplied to line 93, the valve 91 opens, as shown in Fig. 7, with the result that pressure is supplied also to the left hand side of the jack piston as the area exposed to pressure of the left hand face of the jack piston is, due to the jack piston rod 26, less than that of the right hand face, the jack piston will move to the left and during the initial stage of the retraction movement, therefore, liquid circulates as shown by the arrows in Fig. 7, and the float is retracted at high speed and low torque. The pressure in the line 93 increases as the load on the jack increases, until the maximum jack pressure is reached. This occurs when the float has travelled through about 69 and the valve I95 then opens, as shown in Fig. 8, admitting pressure to the space between the pistons I9I, I92. These move apart, closing the valve 99 and causing the tappet I93 to open the non-return valve 95. Pressure is thus disconnected from the left hand end of the jack cylinder and liquid can flow from that end of the cylinder to line I91, and thence to the return line 81 through a pressure sequence valve I98 and the mechanical sequence valve 49, these valves being lifted against their respective springs I99, I49.

The float continues to move up at a slower speed and, when the outboard up locks 31 have closed, the resultant closure of switches 31 (Fig. 5) energises the solenoid 58 as already described and thereby opens the magnetic sequence valve 38. Pressure is then fed to the float lock 29, opening that lock. A pressure sequence valve I I9 then opens against its spring I I I, and admits pressure to the left hand end of the cylinder of the float splitting jack 39. Fluid is expelled from the right hand end of this cylinder to the return line 81 through a pressure sequence valve II2 which opens against its spring I I3.

The two sections of the float then separate and, when the inboard up lock 48 has closed, the motor 35 of the power jack is stopped, as already described, by the opening of switch 48 (Fig. 5). When the motor 35 is switched off, the non-return valve 95 of the change over valve closes and the pistons I9 I, I92 return to the position of Fig. 6 expelling liquid through the non-return valve 98, and valve I95 closes.

Lowering the floats It has already been explained that, on movement of the lever 39 (Fig. 5) from the up! contacts 33to the down contacts 34, the power pack motor 35 is started and that the motor 45 is also started to move the valve into float-lowerarcades ing position. line: '81" isthen' connecte'd'to the pressure line 85 and line 86 to the exhaust line 88. PIGSSUIBJ thus first applied to the inboard up lock '48. to open thatlock. The pressure sequence valve 2 then opens applying pressure. to the righthand end oftthecylinderof the float splitting'jack 3.9,- liquid. being. expelled from the left hand end; ofithat cylinder-,throughthevalves III), 38 and SI, to the returnline', and the jack. operating to collapse" theoutboardsection of thefloatagainst theinboardsection. When therfloat lock 20 closes, as the result of the twosections of the float coming together, it opens the-me chanical sequence. valve-49 as already described;

Pressure. is then applied to i the outboard .up locks 31, openingithem'. After the locks have opened, the pressure sequence valve I08: opens, supplying pressure to the changeover valve 94-. The-nonreturn valve. 95 openssupplying pressure tothe left hand end of'th'e' cylinder'of'thefloat raising jack, causing the sameto lower the float. Liquid flows to the return line from. the right handend" of this cylinder through the valve 9'I. During lowering of. the 'floa-t the-jack 21 operates in a single stage. only. When thefloat'hasbeen low-- ered, the down lock. 29 closesand stops the motor 35, as already described, by openingthe switch A relief valve I24, opening at 1000 lbs/sq. in., is interposed-between the lines 81, 88'

20 (Fig.

so as to keep the load down during-lowering of the. floats, as only comparatively small power is needed for lowering. The non-return valve 98 closes so that the restricted passage I25 affords the sole passage through which liquid may 'flow to return during the lowering operation. This retards movement of the float to the down' position.

Emergency Operation An emergency air system, shown in chain dotted lines in Fig. 6, isv provided for lowering the floats in case of failure of the hydraulic air is fed to the outboard up locks 37 toopen them. The. switch. I26. isthen moved to contact H8, energizing a.v solenoid II-9 to open a valve Compressed: air-:i's then supplied, via a line I20. I2 I,.to the two jacks-27,39. simultaneously, thereby causing the float to move to the down position, in which it will be locked by the float lock 20 anddownlock29.

Shuttle valves I22 are fitted to the up locks 31', 48 and to the jacks 21, 39.. When-air is admitted to the line I16, the shuttle valves I22 associated with the locks open to supply air to the locks to move their hooks toopen position against the action of their springs. When the shuttle valves I22 open, they disconnect the looks from the lines which normally feed oil to them, so that the air pressure cannot escape through a fractured oil pipe. The shuttle valves I22 associated with the jacks 21 and 39 similarly open, when air pressure is supplied to the line I2I, to admit air to the left hand end of the cylinder of the jack 2'! and to the right hand end of the cylinder of the jack 39 and to cut on these ends of the cylinder from the associated oil pipes.

Each jack is fitted with an emergency air releaseva-lve I 23, whichzisa opne d by the air pres sure :when the valve 1 I20 opens; to aflord an. outlet to atmosphereior'oilexpelledifrom the. jack cylinders: as the Jacks are Operated by the air pres-'- sure'to closeiupand lower the'float.

What: It claim: as my: invention and desire to: secure by Letters Patent 1. In; an. aircraft, comprisinga'. wing and a stabilising float? divided into twoi-por-tions hinged? together alongthe keel. line of. thefloat, the: coma bination with saidifloatmfi a; float lock fOlflOClC- in'g'thettwo portions of thezfloatntogether, a first power" operatediretractorforrretrazcting the floatlaterally; andwiththeitwoportions thereof locked together, to introduce; one portion of: the. float: into. a. recess in the wing, meansresponsive'to: theentry of said p'ortiominto saidrecess for automatically releasingatheflorat lock, and a second power' operated; retractor; renderedi operative by release of said: floatrlociaiorseparating thG tWOT portionsroithafloat.

2.. In; an aircraft,v comprising: a wing and; ai stabilising float divided into twoportionsz hingedv together? along. the. "keel. line of the. float, the. combination with said. float of: afloat;- loclnfor locking'the' twcr portions of the float to; gether, a first" power: operated retractor for." re.- tracting thefloatlaterallya in an inboard direction, and withrthestwozportionsmhereof lockeditogether; to: introduce one portionof: the float. into: a recess. in. the; wing; an up look for locking said; portion: to.- the:- Wing, means; responsive: to; operation of. said up loclr' forsautomatically releasing the;float; lock, and a;secondipowerroperated retractor; remdered operative by release of .said zfloatilock', for

separating: the: two portions of the. float.

3. In .an' aircraft,comprising. a; wing anda star bilising float divided into two. portions; hinged:

together along, thakeelline of: the flbat,.the:combinationawith saidifloat of; a; floatrlock for locking: the. two portions otthe' float together, a." first; hydraulic jack. for: retracting; the: float. laterally; and withthe: two? portions? thereof locked to;-

gether, to-introduce one portion. of; the float into;

a recess; in thawing, means: responsive. to the: entryof said portion into said recess for autos matically releasing. the: float. lock; and a. second:

hydraulic. jack, rendered operative byrreleasev 0t.

a piston: rod projecting-airmone end of: the?! cylinder, apump forrsupplying. motive fluid; tfo-thes jack cylinder; andia: two-stage. change-over valve.

responsive tothe hydraulic: pressure: delivered. by said. pump to: said. cylinder; said: changes-over valveinitiallvsunplying pressure fluid t both:

ends of saidv cylinder: but operating automatical 1y. at .aapredeterminedzhydraulicxpressure, to COIL-- neat. to: exhaust. the end of; the: whichasaidzpiston rod-projects;

5. In an aircraft, comprising a wing and a stabilising float divided into two portions hinged together along the keel line of the float, the combination with said float of a float lock for locking the two portions of the float together, a structure supporting the float and hinged to the wing, a down lock for locking said structure in position to support the float in the down position, a first power operated retractor, a second power operated retractor, control devices for respectively recylinder from leasing the down lock, operating the first retractor to retract the float laterally into the wing, releasing the float lock and operating the second retractor to separate the two portions of the float, and means operable by the pilot for rendering said control devices successively efiective to retract said float into said wing.

6. In an aircraft, having a wing and a stabilising float divided into two portions hinged together along the keel line, the combination with said float of a lock for holding the two portions together, a hydraulic jack in the wing for retracting the float laterally and in an inboard direction, without release of the lock or separation of its two component portions, until the inboard portion thereof has entered a recess in the wing, an outboard up lock in the wing for locking the inboard portion of the float in its recess, a jack in the float for effecting relative movement of the two portions of the float, an inboard up lock in the wing for locking the outboard portion of the float in a recess in the wing, a down lock for locking the float in the down position, all of said locks being arranged to close mechanically on contact of the part to be locked with the lock and to release hydraulically, a hydraulic pump, means controlled by the pilot for starting the pump, a hydraulic circuit for the fluid delivered by the pump, valves in said circuit, and means for operating said valves automatically and in sequence to direct said fluid first to the down lock to release it, then to the jack in the wing to raise the float, then to the float lock to release it and finally to the jack in the float to separate the portions of the float.

'7. In a hydraulic retracting gear for an aircraft float split into two relatively movable sections, the combination of a, hydraulic pump, a hydraulically releasable down lock for locking the float in the down position, a hydraulically releasable float lock for holding the two sections of the float together, a first hydraulic jack for raising and lowering the float, a second hydraulic jack for separating and returning the two sections of the float, a hydraulic circuit for supplying fluid from said pump to said locks and jacks, a control valve operable by the pilot to supply fluid from said pump to said circuit to open said down lock, 2.

pressure sequence valve in said circuit arranged to open, in response to opening of said down lock to supply fluid to said first jack to raise the float, an up look arranged tobe closed by the float to lock the float in the raised position, and a valve in said circuit operable by closure of said up lock to supply fluid to said float lock to open said float lock, and a pressure sequence valve in said circuit arranged to open, in response to opening of said float lock, to supply fluid to said second jack to efiect separation of the two sections of said float.

8. Apparatus as claimed in claim 3, including an emergency pneumatic float lowering gear comprising a reservoir of compressed gas, and a valve operable by the pilot to supply compressed gas from said reservoir to said jacks, said compressed gas being efiective to operate said jacks to lower '12 the float and to approach its two portions together.

9. In an aircraft, having a wing and a stabilising float divided into two portions hinged together along the keel line, the combination with said float of a lock for holding the two portions together, a hydraulic jack in the wing for retracting the float laterally and in an inboard direction, without release of the lock or separation of its two component portions, until the inboard portion thereof has entered a recess in the wing, an outboard up look in the wing for locking the inboard portion of the float in its recess, a jack in the float for effecting relative movement of the two portions of the float, an inboard up look in the wing for locking the outboard portion of the float in a recess in the wing, a down lock for locking the float in the down position, all of said locks being arranged to close mechanically on contact of the part to be locked with the lock and to release hydraulically, a hydraulic pump, means controlled by the pilot for starting the pump, a hydraulic circuit for the fluid delivered by the pump, fluid directing valves in said circuit, a reversing valve for reversing the direction of circulation of fluid by said pump and means for effecting alternative control over said fluid directing valves, according to the position of said reversing valve, to actuate said locks and jacks to raise and lower said float.

10. Apparatus as claimed in claim 9, a switch movable by the pilot to alternative positions to select raising and lowering movement of the float, and electromagnetic means energised by movement of said switch to start said motor and to actuate the reversing valve to select the appropriate direction for circulation of fluid in said circuit.

11. Apparatus as claimed in claim 10, comprising a pair of switches for switching off said motor, one of said switches being linked to the inboard up lock and operable by closure thereof at the conclusion of the float retracting operation and the other of said switches being linked to the down lock and operable by closure thereof at the conclusion of the float lowering operation.

12. Apparatus as claimed in claim 11, comprising further switches associated with the inboard up look and the down lock and arranged to occupy alternative positions according as whether the associated locks are released or closed, warning lamps, and circuits controlled by said further switches to energise said warning lamps to show to the pilot the position of the float.

EDWARD JAMES NICHOLL.

REFERENCES CITED The following references are of record in the file of this patent: 1

UNITED STATES PATENTS Number Name Date 2,204,457 Vogt June 11, 1940 2,285,330 Dowden June 2, 1942 

